Gatling vs Locust 2026: Load Testing Compared
Gatling vs Locust 2026: Scala DSL vs Python, throughput, reporting, distributed execution.
Gatling
Scala/Java-based high-performance load testing
- License
- Apache 2.0
- Language
- Scala / Java / Kotlin
Locust
Python-based open-source load testing
- License
- MIT
- Language
- Python
Gatling and Locust are two open-source load testing tools written in different host languages. Gatling uses a Scala DSL (also Java + Kotlin since v3.7) and runs on the JVM with high VU density. Locust uses Python with greenlets and ships a live web UI. Throughput-wise Gatling typically wins; ergonomics-wise depends on team language preference.
Feature-by-Feature Comparison
| Feature | Gatling | Locust |
|---|---|---|
| Host language | Scala / Java / Kotlin | Python |
| Runtime | JVM | Python with gevent |
| Max VUs per host | 50K+ | 5K-10K |
| Web UI | No (HTML report post-run) | Built-in live UI |
| Distributed | Gatling Enterprise (paid) | locust --master/--worker |
| Protocols | HTTP/JMS/SSE/gRPC/MQTT | HTTP/WebSocket + custom |
| Reporting | Detailed HTML + charts | CSV + live UI |
| CI integration | Maven/Gradle/SBT/JUnit XML | CLI exit codes |
| Learning curve | Days (Scala DSL) | Hours (Python) |
| License | Apache 2.0 (Enterprise commercial) | MIT |
Strengths of Gatling
- •High VU density per host
- •Detailed HTML report out of the box
- •JVM ecosystem integration
- •Scala DSL is concise
- •Java/Kotlin support since 3.7
- •Strong CI integration (Maven/Gradle/SBT)
- •Used in enterprise
- •Active development
Strengths of Locust
- •Python-native — no Scala learning curve
- •Live web UI during test
- •MIT license
- •Easier custom user behavior
- •Great fit for Django/Flask teams
- •Distributed mode free
- •Pythonic asyncio support
- •Free and self-hosted
When to pick Gatling
Pick Gatling for JVM teams, when VU density matters, when detailed reports out-of-the-box are needed, or when Scala DSL fits team skills.
When to pick Locust
Pick Locust for Python teams, when MIT license is required, when live UI during runs matters, or when distributed mode must be free.
Verdict
Gatling for JVM + max density. Locust for Python + free distributed + live UI.
Frequently Asked Questions
Which has higher throughput?
Gatling typically 5-10x higher VUs/host due to JVM + non-blocking async I/O.
Live UI?
Locust ships one. Gatling shows HTML report post-run.
CI integration?
Gatling exports JUnit XML via maven-surefire. Locust uses CLI exit codes + custom parsing.
Scala or Java for Gatling?
Scala still the canonical DSL. Java DSL (v3.7+) works fine for Java teams.
Deep-Dive Articles
Need a ready-made testing skill?
Both Gatling and Locust have curated QASkills.sh skills you can install into Claude Code, Cursor, Copilot in 5 seconds.
Comparisons reflect public information as of 2026-05. Tooling evolves quickly — verify current state on official docs before final decisions.